This trial is a randomized, double blind, controlled pilot study that will compare bilateral theta burst stimulation (TBS) and sham treatment for patients with opioid use disorder (OUD) and Major Depressive Disorder (MDD) experiencing suicidality.

Repetitive transcranial magnetic stimulation (rTMS) to the dorsolateral prefrontal cortex (DLPFC) is used therapeutically in major depressive disorder resistant to standard treatments, and recently also shown to be effective in reducing suicidality with a bilateral approach. Recently, a new form of rTMS has been developed called theta burst stimulation (TBS) which requires a much shorter daily treatment duration and has been found to be non-inferior to standard rTMS. The investigators propose to conduct a randomized controlled clinical trial of a daily, 20 session course of bilateral TBS versus sham stimulation in the treatment of suicidality in patients with OUD and MDD. The investigators will explore whether TBS can have other clinical effects on decreasing symptoms of MDD, craving for opioids, and rates of relapse to opioid use. The investigators will also examine whether rTMS can engage GABA mediated inhibition using combined transcranial magnetic stimulation and electroencephalography (TMS-EEG) will be assessed before and after intervention. Clinical outcomes measured before, during, at end of treatment, and 4-weeks post treatment.

Inclusion Criteria:

1. Capable of providing informed consent and research procedures according to the brain stimulation attending psychiatrist
2. Between the ages of 18-60 years
3. Mini-International Neuropsychiatric Interview (MINI) confirmed diagnosis of Opioid Dependence and MDD.
4. On a stable treatment regimen without any change in opioid agonist or antidepressant medications or dosages in the last 30 days. Participants will be asked not to change their medication regimen for the duration of the study.
5. Baseline score of >/=4 on the scale for suicidal ideation (SSI).

Exclusion Criteria:

1. Currently pregnant or intending to be pregnant during the duration of the study
2. Bipolar disorder, any psychotic disorder or current psychotic symptoms
3. Previous rTMS treatment
4. Known active seizure disorder, significant head injury with an imaging verified lesion
5. Unstable medical illness
6. Presence of cardiac pacemaker, intracranial implant, or metal in the cranium
7. Participants taking > 2 mg lorazepam (or a benzodiazepine at an equivalent dose) or taking any anticonvulsant medication during treatment.